Conventional collapsible rollators or wheelchairs often use flexible seats made of canvas or similar non-rigid material. However, such seats do not offer the ideally required level of comfort for the user. Thus, rigid foldable seats have been developed. Such seats are generally hinged in their middle to enable the rollators or wheelchairs to be easily folded into a storage position. Therefore, these two-piece seats define at least two positions of use, an unfolded one, in which the pieces are aligned in the same plane, and a folded one, in which the pieces define an angle less than 180°, and preferably, an angle approximately equal to zero.
To prevent these two-piece seats from folding upwardly or downwardly from their unfolded position, it is known by the man skilled in the art to use locking means which prevents the rotation of the two elements forming the seat. It is also known by the man skilled in the art to use unlocking means so as to allow the rotation of the two elements forming the seat from a locked unfolded position. In particular, such locking and unlocking means have been disclosed in the prior art documents U.S. Pat. No. 7,108,004 B2 and EP 1 244 413 B1, which are incorporated herein by reference in their entirety.
In the document U.S. Pat. No. 7,108,004 B2, the seating structure includes a right side support rotatably mounted on the right side frame of a rollator and a left side support rotatably mounted on the left side frame of said rollator. The right side and left side supports are pivotally interconnected by a first hinge extending along the top surface of the right side and left side supports, and a hinged link, in the form of a tension-rod plate, pivotally interconnecting the bottom surfaces of the right and left side supports. The tension-rod plate is comprised of a first and second solid links pivotally connected to the frame of said rollator, said links being interconnecting by a second hinge, which is positioned directly below the first hinge and parallel thereto. Force-transmitting struts extend diagonally downward from either side of the first hinge to proximate the ends of the first and second solid links. In this prior art, the locking means consists in a spring clip extending from the first solid link and one of the force-transmitting struts and the unlocking means consists in a strap, which extends through openings in the first and second solid links, the force-transmitting struts and the right and left side supports, initial force pulling up on the strap disengaging the spring clip, enabling the right and left side support to pivot towards each other. One of the drawbacks of this solution is its relative complexity. Indeed, it implies the use of an additional tension-rod plate positioned below the seating structure itself. Another drawback is the impossibility for the user to lock the seating structure in a folded position. Finally, the presence of the strap above the top surface of the seating structure implies that the seat covers includes a shallow recess for receiving the strap to ensure the strap does not cause discomfort to anyone sitting on the seating structure. Therefore, this solution implies increased production costs. Furthermore, it implies that nobody is sitting in the rollator to unlock the seating structure.
In the document EP 1 244 413 B1, the seating structure of a rollator consists in a foldable or hinge joint platform which takes, in the rolling position, a stretched position in a substantially horizontal plane, halves of said platform being pivotally connected in the vertical plane of symmetry of the rollator and being each pivotally mounted to the assembly of frame tubes on a respective side of the rollator for an upward folding movement. In this prior art, the locking means consists in a substantially Z-shaped locking element, which is resiliently received in a center piece of the platform and extends with its upper flange portion forwardly over the upper end of the central piece. The locking element is provided with a locking cam, which, in the unfolded position of the seating structure, engages a rearwardly extending locking edge of a guide piece, which is positioned under the platform. In this way, the central piece and the guide piece are locked relative to one another, which excludes undesired folding of the rollator. To enable folding of the rollator, the locking element may be simply depressed downwards, as a result of which the locking cam gets disengaged from the locking edge. Like the previous document, one of the drawbacks of this solution is the impossibility for the user to lock the seating structure in a folded position. Another drawback is the risk that an unwanted unlock of the seating structure occurs when the user is sitting on the locking element. Therefore, this solution is relatively unsafe.
The aim of the present invention is therefore to provide a foldable seat for a rollator or a wheelchair, wherein the drawbacks mentioned of the known foldable seat is avoided.